In the container manufacturing industry in recent years a new class of printing inks has come into wide spread usage. These inks are water based, pigmented compositions, are commonly available commercially, and are typically fast drying.
In a typical printing operation the printing press is washed down after a color change and at the end of a working day. A typical press may thus be washed down anywhere from 1 to 10 times a day using from 20 to 50 gallons of water per washdown. Each such washdown operation produces as waste a diluted ink water which heretofore has commonly been discharged into the nearest sewer at a rate which typically can range from about 200 to 3000 gallons per day. Such diluted ink water contains, among other contaminating impurities, iron, lead, and copper salts, as well as cyanides, chromates, and the like. Organic matter used in formulating such inks, including phenol and certain other hydrocarbons, may be present. Commonly, such ink water also contains finely divided colloidal particles, such as pigments. Such waste water has become a significant environmental pollutant.
Also in recent years, the container manufacturing industry has come to make extensive use of starch based adhesives, particularly in the manufacture of corrugated paper board and the like. A starch based adhesive is charged to a pan on a corrugator, applied therefrom to paper, the paper is contacted with other paper to make corrugated board, and the board product is heated to set and dry the adhesive. Typically, about once a day, starch pans are washed which produces a waste water containing starch. In addition, sometimes a partial batch of a starch based adhesive is dumped for various reasons. Commonly, these operations produce about 300 gallons of waste water per day.
Further, at a typical manufacturing site, adhesive making equipment is found, usually located in a so-called "starch room". The starch room and the equipment therein are commonly washed down about once a week using about 400 to 500 gallons of water.
The wash water from such starch adhesive clean up operations usually contains not only starch and other organic materials employed in starch adhesives (such as phenol, resorcinal, and resinous materials sometimes conventionally used in starch adhesive formulations), but also oily hydrocarbon materials from the machines used to produce corrugated and other containers. This waste water has an extremely high content of suspended solids, being on the order of from about 2000 to 60,000 parts solids per million parts water. The B.O.D. levels in such starch waste water commonly range from about 2000 to 14000 parts per million. Measurements herein are generally made according to the procedures given in the 13th edition of the U.S. Public Health Service publication "Standard Methods for the Analysis of Water and Waste Water". Such waste water has thus become a significant environmental pollutant which has been heretofore commonly discharged into the environment through the nearest sewer.
Recently, direct discharge of both such waste waters into sewers has become a violation of law, as has direct discharge to the ground or surface waters. Normal biological bacterial degradation is not suitable because of the high toxicity and concentration of such waste waters. Such waste waters actually dye and discolor river and sewage streams upon discharge thereinto. No acceptable means has been heretofore available for treating such waste waters to avoid environmental pollution therewith.
There is a strong need in the art for a system which will handle all wastes generated in a container manufacturing facility either singly or in combination. Such system must produce an effluent which can be discharged into substantially any approved sewer treatment system or, alternatively, which can be recycled for the manufacture of starch adhesives or recycled for washdown of water based or commonly termed "Flexographic" inks. Recycling is particularly attractive since if a manufacturer recycles he can never be in violation of law because no contamination is leaving his plant(s). Solid wastes recovered can leave the plant(s) for use as sanitary land fill or the like without polluting water provided that this fill contains no leachable substances which can contaminate run-off water. Development of a suitable waste water disposal system for container plants and the like has proven to be a formidable problem to solve.